Whenever an illness, a disease or one or more symptoms are to be treated, it requires a diagnosis of the underlying disease or disorder. Many symptoms can arise from several diseases, including both physical and mental diseases. Therefore the diagnosis of the disease is of paramount importance for the succeeding treatment. The outcome of a treatment can in many cases depend on the progression of the disease, and therefore on the time elapsed prior to diagnosis, early intervention may be very important. However, in order for a patient to seek medical assistance at least some symptoms needs to be present. Very often a disease may develop without the patient being aware of this, as for example in various cancer diseases and lifestyle diseases, such as e.g. atherosclerosis, coronary heart disease, diabetes, hypertension, liver fibrosis, chronic obstructive lung disease, etc.
Some diseases can be more effectively cured or even avoided if preventive steps such as lifestyle changes are introduced in time. Therefore it has also become increasingly common to participate in health screenings. Health screenings very often do not have any symptoms to rely on as a starting point. To establish a diagnosis for a patient, whether symptoms already exist or it is in relation to a health screening, the physician needs a starting point for the elucidation.
Previously the “Erythrocyte sedimentation rate” (also denoted sedimentation rate) has been widely used as an indicator of the presence of inflammation. The sedimentation rate is the rate at which red blood cells precipitate in a period of 1 hour. When an inflammatory process is present, the high proportion of fibrinogen in the blood causes red blood cells to stick to each other. The sedimentation rate is increased by any cause or focus of inflammation. The basal sedimentation rate is slightly higher in women and tends to rise with age. The usefulness of the sedimentation rate in asymptomatic persons is however limited by its low sensitivity and specificity, but it has been used as a sort of sickness index, when a moderate suspicion of disease was present.
At present the biomarker C-reactive protein (CRP) has mostly taken over from the previously used sedimentation rate in initial screenings for inflammation. CRP is an indicator of acute or chronic inflammation or infection, and is therefore a test of value in medicine, reflecting the presence and intensity of inflammation, although an elevation in C-reactive protein is not the telltale diagnostic sign of any one condition. Conditions which can cause a positive response in the serum CRP level are for example rheumatoid arthritis, lupus, rheumatic fever, cancer, hearth disease, cardiovascular disease, inflammatory bowel disease, and bacterial or viral infections. However not all patients with these diseases have an elevated serum CRP level, and for these patients the serum CRP level cannot be used as a sickness-index.